Controlling Garden Pests Organically with BT (Bacillus thuringiensis)

Control corn worms with Bt

As organic gardeners, it’s important to effectively control pests from eating and ruining your crops. BT, which stands for Bacillus thuringiensis, is a naturally-occurring bacteria that makes pests sick when they eat it. Not only is it very effective, its safe in the garden as it’s not made up of harmful chemicals, rather just a natural bacteria found in nature.

There are two types of Bt

Bacillus thuringiensis kurstaki (Btk) is excellent at controlling pests that like to eat leaves, such as caterpillars, cabbage worms and tomato hornworms, however, it has no resistance against non-leaf eating bugs. Bt is the one of the safest natural pesticides you can use for controlling these types of crop-eating insects.

Bacillus thuringiensis israelensis (Bti) is another form of Bt which is primarily used for controlling fungus gnats in greenhouses, or houseplants in your home. Bti is also great for preventing mosquitos in standing water that cannot be drained or controlled with fish. If you have houseplants and notice tiny little gnats flying around, they can be a challenge to get rid of. Bti seems to be one of the best organic methods for eliminating such pests.

Pests that Bt can help you control in your garden

Some common types of pests that Bt will help keep away are caterpillars, armyworms, cabbage worms, diamondback moths, melon worms, corn earworms, green clover worms, pickleworms, tomato fruit worms, tomato hornworms, grape leafrollers, grapeleaf skeltonizers, salt marsh caterpillars, and various webworms and budworms.

Pictured to the left is a common corn worm. These little guys will consume an entire ear in a matter of hours! You may be outside in the afternoon looking at your corn, and everything looks great. Then the next morning you wake up massive damage. Be sure to spray preventatively, even if you don’t see any pests, it’s a good idea to spray Bt regularly to ensure you don’t get invaded. Once they’ve made your garden your home, it could be challenging getting rid of them.

Using Bt effectively

Bt is best applied late in the day as the sun is getting ready to set (or has already set). Reason being, sunlight degrades Bt after a few hours, so by applying once the sun has set will ensure highest effectiveness going forward. Also, the types of pests it controls are generally out at night eating.

Applying Bt is easy. You’ll want to fill a spray bottle with it, and simply spray the tops/bottoms of the leaves where you’re finding bugs eating them. Apply every 7-10 days to ensure pests remain at bay. Be sure to follow the directions, especially if you have purchased concentrated Bt, as you’ll need to mix it with water.

While Bt is very safe and an organic method for controlling certain pests, always remember to wash your hands well after using it.

Storing Bt

Mix only what you need, or what you’ll use within a few days. You do not want to store your Bt mixture for much longer than a few days, as it will quickly degrade and become ineffective. Keep out of sunlight. Store in a dark, cool location out of the reach of children or pets. You can also purchase powdered or other dry Bt products which have a shelf of about 5 years, while the liquid version will last about 3 years if stored properly.

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